Lock nut



Dc; 1s, 1945. L* TARWATERUAL 2,391,219

Y* I vLock NUT I Filed Dec. 29, 1941 IML \ immuun-mlm Alfa/my.-

Patented Dec. 18, 1945 uivi'ii'nA f- STATE-s PATENT oFFicE lassumo e mmm.

Imvson Tarwater and Wendell R. McKenzie, Los Angeles, Calif., assignors of ten percent to Six Wheels, Inc., Los o! California f Angeles, Calif., a corporation mutation December 29, 1941, sesamo. 424,176 s cmms. (c1. rs1-i9) Our invention relates Ito nut lock constructions of that character embodying two members superimposed on a bolt, and provided with cams the bolt extends. Thus is produced a nut lock n construction, which when once locked, not only coacting, when'rotated relatively, t0 setup lateral or transverse stresses between the members and the bolt. which operate to jam the members against the bolt and thus lock the members onl the bolt.

Nut lock constructions of this character -have been found to be faulty because the cams cannot be rotated relativelyto lock or unlock the members without holding one of the members with a wrench while turning the other. Also, because the degree of eccentricity of the cams in relation to the depth of the-bolt threads, the cams are rotatable relatively just to the 180 degree position and no further without effecting permanent distortion ofthe threads of the bolt and members,

and in this position they vdo not remain when subjected to intense vibration, so that their locking effect is lost. r

- It is the purpose of ou'r invention to provide a nut lock construction of the above described character. which has means associated with the two members by which the cams thereofpmay be rotated relatively to a 180 degree locked position and subsequently released by reverse rotation relatively, without the necessity of holding one of the members with a wrench while turning the other. y f

Itis also purpose o t our invention to provide a nut lock construction, wherein the eccentricity of the cams ofthe two members is designed in a predetermined ratio witlri respect to the depth of the threads of the bolt to which the members constructions, each embodying our invention, and

will then point out the novelfeatures thereof in claims.

In the accompanying drawing:

Fig. 1 is a view showing `in vertical'section one form of nut lock construction embodying our invention. v f h Fig. 2 is a view, partly in section, showing our nut lock construction applied to a bolt and in locked position, with the bolt extending through the plates of a piece of work. i

Fig. 3 is a view showing in elevation and partly in section another form of nut lockconstruction applied to a bolt, and.where thelock nutY and washery are in released position with respect to the bolt.

Fig. 4 is a view similar to Fig. l, showing another form of lock nut construction vembodying our invention and in applied position to a bolt.

Fig. 5 is a View similar to Fig. 4 and showing the same in nut-locking position as distinguished from the non-locking position shown in Fig. 4.

'Similar reference characters refer" to similar parts i-n each of the several views.

are applied. This ratio of cam eccentricity to. A

Referring irst to Figs. 1 and 2, our invention in this embodiment comprises an interiorly threaded nut member, which may' be in the form of a lock nut I5 having a lock member inthe form of a lock washer i 6 superimposed on the threaded shank I1 of a bolt I8 extended through plates I9 for holding the plates together. v

At that side 20 of the lock nut l5 confronting the side 2 i of `the lock washer which, in the present instance, is the lower side, the lock nut is position, and maintaining'this locking action in a lesser degree, when the cams pass the 180 degree position. Once the cams pass the 180 degree position any tendency of one or both of the members to unscrew, will be resisted positively by the high points of the cams, and, in practice it has been found that under vibration of the members and the bolt, any turning tendency is a screwing action to further advance the members inwardly on the `boltancl thereby increase the clamping action of the members andbolt in respect to the plates or other work through which formed with a collar 22 which is interiorly threaded in continuation of the threads ofthe bore of the lock nut. 'I'he outer periphery of the collar 22, which is considerably inset ,from

the outer and hexagonal'periphery of Ythe lock` nut, is eccentric to both the bore of the nut and the collar, to provide an annular cam 23. 'I'his A'cam 23 extends the full height of the col1ar, v

although the collar is increased in thickness at its lower marginal end toV form an annular shoulder 24 on the outer periphery thereof.

The lock washer I6, which is of the .same outside dimensions as the lock nut I5,is likewise of hexagonal form, sothat a single wrench may be employed to. screw the lock nut on and oil the bolt shank I1, and at the same time hold the lock ning the two cams 23 and 25 are struck from the same center, and this center is offset with respect to the major axis A of the bolt shank, approximately at; of an inch where the lock nut and lock washer are designed for use on a, one inch bolt having standard size threads. By this offsetting Vthe eccentricity of the cams becomes about 1A of' the depth of the threads of the bolt, and this degree of eccentricity has been found to be suitable to permit turning of the lock nut relative to the lock washer, from a position in which the cams 23 and 25 are concentric one to the other, to a 180 degree position wherein the high points of the cams are opposed, and beyond this 180 degree position, without effecting permanent distortion of the threads of the nut, washer or bolt. f

While the cam 25 extends the full height of the lock washer I6, the inner periphery of the washer is formed at its upper edge with an annular tongue 26 which, while allowing the requisite free axial movement of the collar 22 in the lock washer, coacts with the annular shoulder 24 to permanently conne the lock washer on the collar. The lock Washer may be mounted on the collar by enlarging the inside diameter of the lock washer through the application of heat, while the outside diameter of the collar may be reduced by chilling the metal.

As shown in Fig. 1, the lock Washer has formed on its side 2l an annular and upstanding flange 21 which is relatively thin so as to be crushed or mashed when pressure is applied edgewise thereto. This flange is one of numerous yieldable means which may be employed to normally and temporarily hold the lock nut spaced from the lock washer incident to moving the cams 23 and 25 relatively for locking the nut on the bolt.

In operation, before the nut I5 and washer I6 are applied to the bolt shank l1, they must be so positioned circumferentially that the cams 23 and 25 are concentric one to the other. This is facilitated through indication of the low points of the two cams 23 and 25, by forming marks M and MI on the nut and the washer at such points. Such marks in practise, however, are on the outer peripheries of the nut and washer, as illustrated in the form shown in Fig. 4.

With the cams concentrically positioned they are in what may be termed` a neutral or non-locking position, so that the nut with the washer in advance thereof may be screwed readily onto the bolt. Here the side of the washer IAB abuts the face of the adjacent plate I9, While the nut side 20 comes intocontact with the flange 21 to prevent it from turning with the nut.

Now by gripping only the nut and turning it in a clock-wise direction, the collar cam 23 is rotated rst through an angle of 180 degrees and then beyond such angle, say for a distance from to 15 degrees. As the cam 23 starts to rotate, the lock nut in moving .down the bolt thread, ex-

erts through the ange 21, a pressure axially of the washer. which operates to force the washer against the adjacent plate i9, and this binds thewasher against turning on the plate. Thus, the washer cam 25 is locked against turning. and the cam 23 continues to turn to the 180 degree position in which its high point is opposed diametricause of the aforedescribed ratio of cam eccentricity to thread depth.

Upon the collar cam 23 passing the 180 degree position, this transverse stress is lessened sufficiently to allow relatively free turning of the nut inwardly on the bolt, so that vibration of the nut will cause it to feed inwardly rather than outwardly, andI thereby further tighten itself on the bolt.

The aforedescribed operation of our nut lock construction is made possible' by the manner in which the ange 21 functions during such operation. This flange 21 may be of a height equal to or greater than the pitch of the thread of the nut, so that as the nut is turned down on the bolt the flange although progressively crushed, functions to resist the meeting of the nut side 20 with the washer side 2|, until the collar cam 23 has rotated to and past the 180 degree position. Were it not for this function of the flange, the nut side 2li would abut and bind against the washer side 2l to the extent of causing the washer and its cam 25 to turn with the collar and its4 cam 23, and thus no effective locking action could be had.

To unscrew the nut, when required, suflicient turning force can be applied by a wrench to rotate the high point of the collar cam 23 backwardly past the high point of the washer cam 25, thereby unlocking the nut. This operation is facilitatedI by reason of the'fact that the amount of crush of the flange 21 which takes place during the locking of the nut, is slightly less than the pitch of the nut thread, and thus the collar cam23 will disengage the washer cam 25 in less than one turn of the nut, and thereby the possibility of the washer turning with the nut byreason of binding thereagainst, is eliminated. This mode of operation is best illustrated in Fig. 3, although in this form of pur construction the washer indicated at 16a, the collar at 22a and the nut at lia, are constructed so that the washer is unattached to the collar as distinguished from the permanent attachment of the Washer to the collar as in Fig. 1.

Referring to Figs. 4 and 5, We have here shown another form of nut lock construction showing another method of permanently attaching the washer to the nut collar. Here the nut I5c is provided with a collar 22e which Iis relatively long and interiorly threaded. The free end of the co1- lar is iianged outwardly to form an annular tongue 28. The washer Ic is relatively wide and is formed interiorly with an annular shoulder 29 which coacts with the tongue 28 to permanently attach the washer to the collar.

As in the first form of our invention, the washer |6c is provided with a flange 21e, while the collar and washer are provided with eccentric cam surfaces 23c and 25e. By a comparison of Figs. 4 and 5, it would be clear that this form of nut lock cams wider the transverse stress set up extends a greater distance along the length of the bolt,I

lar flange toward said shoulder which is adapted lof to be mashed down when the nut is threaded down on a bolt toward the work and against the washer.

2. A lock nut as defined in claim 1, in which v the flange has a contact surface Vmaterially less than the reverse side of the washer.

3. A lock nut as denedin claim 1, in which the eccentricity of the cam surface is less tha the depth of the thread of the bolt.

WENDELL R. McKENz'iE. LAWSON TARWA'I'ER. 

